Session E03: Atomic Molecular and Optical Physics II

Squeezing the Most of Heisenberg Using a Bose-Einstein Condensate

Heisenberg’s uncertainty principle establishes a “standard quantum limit” of measurement precision that sets a bound on many precision measurements including atomic clocks and gravitational wave detectors. Using a special class of entangled quantum states known as squeezed states, it is possible to exceed the standard quantum limit. I will discuss experiments with spin-1 atomic Bose-Einstein condensates where dynamical evolution creates spin-squeezed states with uncertainties an order of magnitude below the standard quantum limit. These experiments demonstrate new methods of manipulating out-of-equilibrium quantum systems, and draw together ideas from classical Hamiltonian dynamics and quantum squeezing of collective states.   

Finite Propagation Effects in a Laser-Dressed Quantum System

In attosecond transient-absorption spectroscopy (ATAS), a weak extreme ultraviolet (XUV) pulse is used in combination with a moderately delayed intense infrared (IR) pulse. This combination allows for changes of the XUV spectrum to be observed as it transits through a sample of atoms or molecules. ATAS allows one to study the excitation, radiative coupling, and time-resolved evolution of the target excited states. For thin samples, the absorption spectrum coincides with that of an isolated particle. For thick samples, however, finite-propagation effects must be taken into account. Here we show how, from the non-diagonal component of the electric susceptibility of an isolated laser-dressed target quantum system, it is possible to predict the change in the XUV spectrum due to a sample of finite thickness. We illustrate this method by applying it to a laser-dressed quantum system featuring few isolated metastable states, and show how finite propagation alters the well-known profile of Autler-Townes splitting.   

The Concept of Frequency based on Impulse

The existence of electromagnetic waves have been proved when the frequency had been measured by Heinrich Herts the man who constructed a device that could measure the total amount of changes in specific time. After that scientist define the Frequency as a number of occurrences of a repeating event per unit of time. But we have taken the concept of frequency from another point of view, Impulse. This means, although the speed of blue light is identical to that of red light and there is no difference, as the frequency of blue light is equal to 700 THz, the blue light beats the detector 700*10$^{12}$ times in the unit of time; or the red light with a frequency equal to 400 THz means the red light beats the detector 400*10$^{12}$ times in a second. This definition will help us to explain many related phenomena such as the basic reason of change in the direction of a wave passing from one medium to another (refraction), redshift (Blueshift), the physical mechanism of detecting color in our eyes, etc. In this paper, we have defined the frequency as an impulse and based on this definition we have explained the basic reason of unexplained phenomena such refraction in detail.